State detection device

Abstract

A state detection device which detects parameters includes a measuring pipe, electrodes, an exciting coil that applies a magnetic field to the fluid, signal lines arranged at angle to the magnetic field such that an electromotive force is generated due to a change with passage of time in the magnetic field, and a state quantifying unit for extracting a ∂A/∂t component from resultant electromotive forces that are detected at the electrodes and the signal lines and are composed of an electromotive force of the ∂A/∂t component irrelevant to a flow velocity of the fluid and resulting from a change with passage of time in the magnetic field and an electromotive force of a v×B component relevant to the flow velocity of the fluid, and extracts a variation factor relevant to the parameter from the ∂A/∂t component to quantify the parameter based on the variation factor.

1. A state detection device that detects a parameter such as a property or state of a fluid, a state of a magnetic field, or a state in a measuring pipe, comprising:
 a measuring pipe through which a fluid flows; 
 at least one electrode in the measuring pipe that detects an electromotive force generated by a magnetic field applied to the fluid and flow of the fluid; 
 an exciting unit including the electrode that applies a time-changing magnetic field symmetrical to an axial plane of the electrode that is perpendicular to an axis of the measuring pipe; 
 at least one signal line that is connected to the electrode at one end thereof at an angle to the magnetic field that is parallel to the axial plane of the electrode, such that an electromotive force is generated by a change with passage of time in the magnetic field; and 
 a state quantifying unit that is connected to the other end of the signal line to extract a ∂A/∂t component from resultant electromotive forces that are detected at the electrode and the signal line and are composed of an electromotive force of the ∂A/∂t component irrelevant to a flow velocity of the fluid and resulting from a change with passage of time in the magnetic field and an electromotive force of a v×B component relevant to the flow velocity of the fluid, and extracts a variation factor relevant to the parameter from the ∂A/∂t component to quantify the parameter based on the variation factor. 
 
     
     
       2. The state detection device according to  claim 1 , wherein the state quantifying unit includes: a signal converting unit that extracts the ∂A/∂t component from resultant electromotive forces that are detected at the electrode and the signal line and are composed of an electromotive force of the ∂A/∂t component irrelevant to a flow velocity of the fluid and resulting from a change with passage of time in the magnetic field and an electromotive force of a v×B component relevant to the flow velocity of the fluid, and extracts a variation factor relevant to the parameter from the ∂A/∂t component; a state storing unit that stores, in advance, the relationship between the variation factor relevant to the parameter and the parameter; and a state outputting unit that outputs the parameter corresponding to the extracted variation factor, based on the relationship stored in the state storing unit. 
     
     
       3. The state detection device according to  claim 2 , wherein the signal line has a portion extending in the same direction as the axial direction of the measuring pipe. 
     
     
       4. The state detection device according to  claim 2  or  3 , wherein the exciting unit includes: an exciting coil having an axis lying in the axial plane of the electrode; and a power source supplying an excitation current to the exciting coil, and the signal converting unit extracts the ∂A/∂t component based on a phase difference or time difference between the resultant electromotive forces and the excitation current. 
     
     
       5. The state detection device according to  claim 4 , wherein the power source supplies an excitation current of a first frequency to the exciting coil, the signal converting unit extracts the ∂A/∂t component based on a phase difference between a component of the first frequency in the resultant electromotive forces and the excitation current, and extracts a value or phase of a variation factor relevant to the parameter from the ∂A/∂t component, and the state storing unit stores in advance the relationship between the value or phase of the variation factor relevant to the parameter and the parameter. 
     
     
       6. The state detection device according to  claim 2  or  3 , wherein the exciting unit includes: an exciting coil having an axis lying in the axial plane of the electrode; and a power source supplying excitation currents to the exciting coil, the currents yielding a plurality of exciting frequencies simultaneously or alternatively, and the signal converting unit extracts the ∂A/∂t component based on amplitudes and phases of at least two frequency components that are obtained simultaneously or alternatively from the resultant electromotive forces. 
     
     
       7. The state detection device according to  claim 6 , wherein the power source supplies excitation currents to the exciting coil, the currents yielding first and second exciting frequencies simultaneously or alternatively, the signal converting unit obtains amplitudes and phases of two components at the first and second frequencies from the resultant electromotive forces, extracts the electromotive force difference between the first and second frequency components as the ∂A/∂t component to extract a value or phase of a variation factor relevant to the parameter from the ∂A/∂t component, and the state storing unit stores in advance the relationship between the value or phase of the variation factor relevant to the parameter and the parameter. 
     
     
       8. The state detection device according to  claim 2  to  3 , wherein the at least one electrode comprises a pair of electrodes disposed opposite to each other across the axis of the measuring pipe and along an axis perpendicular to the axis of the measuring pipe, and the at least one signal line comprises two signal lines connected to the electrodes respectively, at least one of the two signal lines being arranged at an angle to a magnetic field that is parallel to the axial plane of the electrodes such that a change with passage of time in the magnetic field generates an electromotive force. 
     
     
       9. The state detection device according to  claim 2  or  3 , wherein the exciting unit includes: an exciting coil having an axis lying in the axial plane of the electrode; and a power source supplying an excitation current to the exciting coil, the at least one signal line comprises a plurality of signal lines arranged in different directions from one another, and the signal converting unit extracts the ∂A/∂t component based on the sum or difference between the resultant electromotive forces obtained from the plurality of signal lines. 
     
     
       10. The state detection device according to  claim 9 , wherein the at least one electrode comprises a pair of electrodes disposed opposite to each other across the axis of the measuring pipe and along an axis perpendicular to the axis of the measuring pipe, the at least one signal line comprises two signal lines that are connected to the electrodes respectively and disposed in the opposite directions from each other from the axial plane of the electrodes, the signal converting unit extracts the ∂A/∂t component based on the sum of the resultant electromotive forces obtained from the two signal lines, and extracts a value or phase of a variation factor relevant to the parameter from the ∂A/∂t component, and the state storing unit stores in advance the relationship between the value or phase of the variation factor relevant to the parameter and the parameter. 
     
     
       11. The state detection device according to  claim 9 , wherein the at least one signal line comprises a plurality of signal lines connected to the same electrode, the signal converting unit extracts the ∂A/∂t component based on an amplitude and phase of the resultant electromotive force obtained from the at least two signal lines among the resultant electromotive forces obtained from the plurality of signal lines. 
     
     
       12. The state detection device according to  claim 11 , wherein the at least one signal line comprises first and second signal lines connected to the same electrode and disposed in the opposite directions from each other from the axial plane of the electrode, the signal converting unit calculates an amplitude and a phase of a first resultant electromotive force obtained from the first signal line and an amplitude and a phase of a second resultant electromotive force obtained from the second signal line and extracts an electromotive force difference between the first and second resultant electromotive forces as the ∂A/∂t component based on the amplitudes and phases to extract a value or phase of a variation factor relevant to the parameter from the ∂A/∂t component, and the state storing unit stores in advance the relationship between the value or phase of the variation factor relevant to the parameter and the parameter. 
     
     
       13. The state detection device according to  claim 11 , wherein the at least one electrode comprises a pair of electrodes disposed opposite to each other across the axis of the measuring pipe and along an axis perpendicular to the axis of the measuring pipe, and the at least one signal line comprises a plurality of signal lines connected to each of the electrodes, the signal lines connected to at least one of the electrodes being arranged at an angle to a magnetic field that is parallel to the axial plane of the electrodes such that a change with passage of time in the magnetic field generates an electromotive force. 
     
     
       14. The state detection device according to any one of  claim 1 , further comprising an outer core that covers the exciting unit, and the at least one signal line is arranged inside of the outer core at an angle to a magnetic field that is parallel to the axial plane of the at least one electrode such that a change with passage of time in the magnetic field generates an electromotive force. 
     
     
       15. The state detection device according to any one of  claim 4 , further comprising an outer core that covers the exciting coil, and the at least one signal line is arranged inside of the outer core at an angle to a magnetic field that is parallel to the axial plane of the at least one electrode such that a change with passage of time in the magnetic field generates an electromotive force.